Abstract: Objective: To clarify the clinical characteristics and current treatment status of pityriasis rubra pilaris (PRP) and to provide evidence for the diagnosis and treatment of this disease. Methods: A retrospective analysis was conducted on the medical records of 66 patients diagnosed with pityriasis rubra pilaris (PRP) at the Dermatology Hospital of Southern Medical University from January 2011 to October 2024. Demographic characteristics, clinical and pathological features, treatment regimens, and therapeutic efficacy were analyzed. Treatment efficacy was classified into complete remission, partial remission, and non-response based on the physician's clinical assessment. Results: Among the 66 patients, 59% were male and 41% were famale. Age-stratified analysis of disease onset showed a first peak at 1-10 years of age and a second peak at 30-40 years of age. Clinically, 87.9% of patients presented with squamous erythema, 37.9% with follicular papules, and 28.8% with palmoplantar hyperkeratosis. Histopathologically, the detection rates of follicular plugging and checkerboard pattern, the classic features of pityriasis rubra pilaris (PRP), were 11.6% and 16.3%, respectively. Characteristic dermatoscopic findings were observed in 82.6% of the 23 patients who underwent dermatoscopy. Regarding treatment outcomes, among conventional therapies, the overall response rate was 43.8% for acitretin, 33.3% for methotrexate, and 25% for cyclosporine, while ustekinumab, a biologic agent, achieved an overall response rate of 81.8%. Conclusion: PRP occurs more frequently in males, with a bimodal age distribution at onset. The predominant clinical presentation is squamous erythema. Classic histopathologic features show low detection rates. Dermatoscopy serves as an effective noninvasive auxiliary tool for diagnosing PRP. Acitretin yields a superior overall response rate compared with other conventional treatments. Ustekinumab demonstrates significant efficacy in the management of refractory PRP.

Key words: pityriasis rubra pilaris, retrospective study, IL-12/23 inhibitors, ustekinumab